Automatic stairway elevator



Feb. 25, 1958 E. T. NORD ET AL AUTOMATIC STAIRWAY ELEVATOR 4 Sheets-Sheet 1 Filed Aug. 2. 1954 INVENTORS Eric T. Nerd Samuel Rosen Feb. 25, 1958 E. T. NORD ET AL AUTOMATIC STAIRWAY ELEVATOR Filed Aug. 2, 1954 II imam 4 Sheets-Sheet 2 INVENTORS Eric T. Nerd Samuel Roseu United States Patent AUTOMATIC STAIRWAY ELEVATOR Eric T. Nord, Oberlin, and Samuel Rosen, Lorain, Ohio, assignors to U. S. Automatic Corporation, Amherst, Ohio, a corporation of Ohio Application August 2, 1954, Serial No. 447,149

4 Claims. (Cl. 187-12) This invention pertains to the art of power hoists or elevators and, more particularly, to an elevator adapted to be installed on a stairway of homes or places of business for transporting people or goods from one level to another.

The present invention in some respects is an improvement upon the appartus described in the application of Bruce Roberts, Serial No. 376,571 filed August 26, 1953, and assigned to the assignee of this application and will be described with particular reference to the apparatus described therein, although it will be appreciated that the invention is not so limited.

In that application, a power hoist adapted to be installed on a stairway is comprised generally of a rail at one side of and extending the length of the stairway, a car movable on the rail and power means at one end of the rail for driving the car in either direction.

The apparatus described has a number of advantages; namely, it is completely symmetrical and, therefore, can be installed without alteration on either side of a stairway; it can be fastened to a stairway without in any way marring the surfaces of the stairway; no rail on the center of the stairway is necessary and a relatively light-weight side rail can be employed without reinforcement because weights on the car spaced from the rail are supported by a skid which progressively engages the lips of the stair treads as the car moves along.

One of the problems with that apparatus and with the prior art in general is the need for a special drive motor having both high starting torque characteristics and relatively large horsepower ratings. High starting torque motors are relatively expensive when considered in relationship to equivalent horsepower motors of a lesser or low starting torque.

Further, such higher horsepower motors, usually horsepower or more, draw so much electric current that the wiring therefor cannot safely be plugged into the ordinary household convenience outlet and special wiring is usually required. This is expensive. Another problem has been the need for speed reducers between the motor and the driving connections for the car. These are usually of the gear type and are expensive and mechanically inefficient.

Still another problem has been the need of positioning the bulky motor at one end or the other of the rail where it is unsightly and interferes with the normal use of the stairway.

The present invention contemplates a stair elevator of the general type described comprising, in combination, a rail adapted to extend the length of a stairway, a car movable on the rail and power means for driving the car in either direction which provides improvements primarily in the power means for driving the car and its control, I

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tion with a speed-operated clutch whereby the motor is not engaged to operate the car until the motor has reached substantially its full operating speed. A motor of relatively low starting-torque characteristics may thus be employed.

The power means also includes energy-storing means, such as a fly wheel, having a total kinetic energy when the car is moving at least percent and, preferably, 1000 percent greater than the maximum kinetic energy of the moving, fully loaded car. Thus, while the total energy to be dissipated on braking is greater, the car may be braked to a stop at approximately the same point in its limits of travel with a minimum variation caused by different car loadings.

Additionally, the power means includes a difierential braking arrangement having greater braking action on the downward movement of the car than on the upward movement and with the braking action in each direction being independently adjustable.

The driving connection between the car and the stairway includes a fixedly mounted nonrotatable threaded shaft extending the length of the stairway and a nut engaged with the shaft and rotatably mounted on the car. The motor drives this nut generally at the rotational speed of the motor, the engagement between the nut and the shaft providing an inherent speed reduction such that no other reduction gears are necessary. The nut and shaft are of a type having high mechanical efficiency.

Further, the power means is provided with a foolproof control arrangement, including means preventing energization of the motor unless its power connections are such as to positively determine its direction of rotation in combination with means for preparing the motor after the car has started for reverse operation when next started, such control arrangement also permitting the use of con ventional low horsepower, low-cost, split-phase electri= motors as the power sources.

Further, in accordance with the invention, emergency stop means are provided for the car including a flexible leading edge extending the width of the car and a bar biased toward said edge and pivotally connected at its center to stop mechanism.

The principal object of the invention is the provision of a new and improved power hoist of the type adapted to be installed on stairways which is relatively simple in construction, economical to manufacture and foolproof in operation.

Another object of the invention is the provision of a new and improved arrangement for stair elevators Whereby variations in loading on the elevator will have a minimum effect on the stopping position of the elevator.

Still another object of the invention is the provision of a new and improved power means for driving an elevator car which includes means having kinetic energy when the car is moving substantially greater than the kinetic energy of the moving fully loaded car.

Still another object of the invention is the provision of a new and improved braking arrangement for stairway elevators which enables the elevator car to be brought to a smooth stop after traveling in either direction and at the limits of travel at approximately the same point regardless of loading.

Another object of the invention is the provision of a new and improved elevator stairway having braking means exerting a greater braking action on the downward movement of the car than on the upward movement.

Another object is the provision of a new and improved power means for stairway elevators including a speedoperated clutch so that the motor may be at full operating speed when mechanically engaged to drive the car and a low-cost, low-starting torque motor may be employed.

Yet another object of the invention is the provision of a new and improved driving connection between the car and the stationary parts which is mechanically efiicient and which inherently provides a speed-reduction function such that independent speed-reduction units will not be required.

Another object of the invention is the provision of a new and improved control circuit which enables a ready control of the movement of the car from either the car or at either limit of its travel which requires a minimum of control wires, which permits the use of low-cost, splitphase motors and which is foolproof.

Another object is the provision of emergency stop means for the car which is mechanically simple and economical to manufacture.

The invention may be embodied in certain parts and arrangements of parts, a preferred embodiment of which will be described in detail in this specification and illustrated in the accompanying drawings which are a part hereof, and wherein:

Figure 1 is a perspective view of a fragmentary portion of a conventional stairway showing a preferred embodiment of the invention mounted on the left-hand side of the stairway;

Figure 2 is an enlarged fragmentary side elevational view of Figure 1 showing in particular the mounting bracket used for the rail, the skid on the outboard side of the car and the emergency stop arrangement;

Figure 3 is a fragmentary view of Figure 2 taken approximately on the line 2-2 thereof and showing details of the emergency stop arrangement;

Figure 4 is a cross-sectional view of Figure 2 taken on the line 4-4 thereof and showing, in particular, the motor and its driving connection with the rotatably mounted nut;

Figure 4a is a fragmentary cross-sectional view of Figure 2 taken approximately on the line 4a-4at thereof and showing the relative mounting of bracket and rail for adjustability;

Figure 4b is a cross-sectional view of Figure 2 taken approximately on the line 4b4b thereof and showing primarily the skid arrangement for supporting the outboard side of the car;

Figure 5 is a fragmentary cross-sectional view of Figure 4 taken approximately on the line 5-5 thereof and showing details of the drive connection between the car and the stationary parts of the apparatus;

Figure 6 is a view similar to Figure 5 and, in effect, is an extension thereof;

Figure 7 is a detail view of Figure 4 showing the automatic braking mechanism in the event the drive belt should break;

Figure 8 is a cross-sectional view of Figure 4 taken approximately on the line 3-8 thereof;

Figure 9 is a cross-sectional view of Figure 8 taken approximately on the line 99 thereof;

Figure 10 is a cross-sectional view of Figure 8 taken approximately on the line 10-10 thereof;

Figure 11 is a cross-sectional view of Figure 8 taken approximately on the line 10-10 thereof and, in effect, is a continuation of Figure 10;

Figure 12 is a fragmentary side elevational view partly in section of Figure 8 tak n approximately on the line 1212 thereof;

Figure 13 is a cross-sectional view of Figure 12 taken approximately on the line 13-13 thereof;

Figure 14 is a schematic wiring diagram showing the control circuit embodying the present invention;

Figure 15 is a view showing an alternative form of skid arrangement;

Figure 16 is an end elevational view of Figure 15 showing details thereof.

Referring now to the drawings wherein the showings are for the purposes of illustration only and not for the purpose of limiting the invention, Figure 1 shows a 4 stairway indicated generally at A with a hoist embodying the present invention installed thereon, the hoist being comprised generally of a rail B and a parallel screw E, a car C and power means D for driving the car up and down the stairway A.

The stairway A forms no part of the present invention, and includes a top step 10 which may be a landing inbetween a pair of Stairways, a step along the stairway or the upper floor to which the stairway leads, a bottom step 11 and a plurality of intermediate steps 12, each including a riser member 13 and a tread 14, each tread extending beyond the riser to form a lip 15 as is conventional in stairways.

The rail B may be mounted on either the right or lefthand side of the stairway but is shown in the figures as being mounted on the left-hand side of the stairway and may be mounted slightly spaced from the wall substan tially as shown. The rail B is generally U shaped in cross section (see Figure 10) with the legs of the U lying in or parallel to the plane of the stairway. Thus, the rail B includes a lower leg or base 18, an upper leg or top 19 and a base or side 20 which interconnects the base 18 and top 19 on the side remote from the wall. The end of the top 19 terminates in an upwardly extending flange 16. The rail B may be manufactured from a fiat strip of steel rolled to the shape shown.

The rail B extends from a point either resting on or slightly spaced from the lower step '11 to a point above the upper step 10 in a straight line and at an angle corresponding to the average slope of the stairway A. The rail B is mounted in the position just indicated by brackets shown generally at 22 having a horizontally extending base 23 (see Figures 1 and 10) and an angular portion 24 which extends parallel to and is fastened to the underside of the rail B.

The bracket 22 is mounted in position with the angle portion fastened rigidly to the underside of the rail B by means of a bolt 27 and the base 23 rests on the upper surface of the tread 14 and extends back toward the riser 13 a substantial distance so that the weight of the hoist transferred to the stairway through the brackets 22 will be transferred at a point substantially removed from the lip 15. The right-hand end of the base 23 terminates in a downwardly extending portion 28 of a length greater than the thickness of the maximum thickness of stair tread which will be encountered and which, itself, then terminates in a reversely bent portion 29 having a bolt or the like 30 threadably mounted therein and cngagcable with the underside of the lip 15.

Preferably, a layer of semiresiiicnt material 32 is positioned between the base 23 and the upper surface of the stair tread 14. This material 32 preferably has a high coefiicient of friction, both with varnished surfaces such as is normally found in stair treads and with steel from which the bracket is preferably made.

The angle of the portion 24 relative to the base 23 is made adjustable so that its angle may be made to conform to the angle of the rail B. This angular adjustment may be provided for in a number of different ways but, in the embodiment of the invention shown, the angle portion is integrally joined with the base portion 23 by an upstanding portion 25 such that by bending the upstanding portion 25 relative to the base 23 and the angle portion 24, its over-all vertical height may be adjusted and, thus, the angle of the angle portion 24 may be adjusted. It will be noted that the free end of the portion 24; that is, the right-hand end as viewed in Figure 23, rests on the right-hand end of the base 23, a rigid construction thus resulting.

The rail is provided With a plurality of generally equally spaced openings 33 along its base into which the screw or bolt 27 extends. The angle portion 24, in turn, has an elongated slot 34 through which this bolt 27 also extends, it being appreciated that with the definite fastening positions along the underside of the rail and the inenemas definite fastening position provided by the slots 34 with the length of the slot 34 being greater than the distance between adjacent openings 33, an unlimited and completely free adjustment of the bracket 22 may be secured relative to the rail B. In addition, it will be noted from Figure 2 that variations in the outer edge of the lips from the slope of the stairway may be compensated for by spacing the vertical portion 28 of the bracket 22 from the outermost end of the lip 15. Once the brackets are properly adjusted and the bolts 30 tightened up, a rigid and extremely strong and vibration-proof mounting of the rail B results.

The car C is comprised essentially of a carriage indicated generally at 65 in Figures 4 and 8 and a platform indicated generally at 66 in Figure 2, which platform 66 is generally removable from the carriage 65, as well as adjustable relative thereto as will appear.

The carriage 65 is comprised generally of a flat steel plate 70 having an upwardly extending flange 71 intermediate its ends, the platform 66 being mounted on this flange 71. The base 70 has two sets of three rollers mounted one set at each end thereof which engage surfaces of the rail B and movably support the carriage 65 for movement along this rail. Thus, in the embodiment of the invention shown (see Figure 4), the lower side of the base 70 is provided with spaced rollers 73, 74 rotatable about a vertical axis; i. e., an axis perpendicular to the length of the rail B and spaced apart so that their opposed surfaces can engage respectively the flange 16 of the top leg 19 of the rail B while the other roller 74 engages the vertical side of the rail B. The third roller 76 is mounted for rotation about an axis parallel to and spaced from the lower side of the base 70 on a downwardly depending flange 77 on the left-hand side of the base 70 as viewed in Figure 4. This roller 76 has a diameter just slightly less than the spacing between the base 18 and top 19 of the rail B and extends between these two members. Thus, the rollers 73, 74 guide the carriage 65 along the length of the rail B while the roller 76 transfers vertical forces to the rail B.

There are three similarly disposed rollers 73', 74' and 76 at the opposite end of the base 70 which engage like portions of the rail B.

The platform 66 is comprised of a step 80 and a riser 81 formed of relatively thin sheet metal bent to the angle shown in Figure 2 and terminating in inwardly extending flanges 82, 83 respectively. The inboard or left-hand edge of the step 8-0 and riser 81 is welded as at 84 to a flat L-shaped mounting plate 85 extending upwardly above the upper surfaces of the step 80 and the riser 81 a short distance as can be seen from Figures 2 and 4. The plate 85 is fastened to the flange 71 in such a manner that the angle of the step 80 can be readily adjusted relative to the angle of the carriage 65 and, thus, the rail B. In the embodiment of the invention shown, three bolts 87, 88 and 89, the latter two equally spaced from the first, extend through aligned openings in the flange 71 on the plate 85 to permit this adjustment. Thus, the bolt 87 passes through oblong openings 9%, 91 in the plate 85 and flange 71 respectively. As shown, the major axis of the opening 99 is at right angles to the major axis of the opening 91. In a like manner, the bolt 88 passes through aligned oblong openings 92 in the plate 85 and 93 in the flange 71, with the major axes thereof oriented at 90 degrees, the same as with reference to the openings 90, 91. It will be noted, however, that the major axis of the opening 92 is at right angles to the axis of the opening 90. The bolt 89 passes through openings 92' and 93' similarly oriented to the openings 92, 93 in the plate 85 on the flange 71 respectively. With the arrangement shown, the platform 66 may thus be adjusted angularly relative to the flange 71 within limited amounts. After the angular adjustment is made, the bolts 87, 88, 89 are tightened as is conventional.

The outer or right-hand end of the platform 66 terminates in an end plate 96 welded to the outer edges of the platform and riser 81.

The plate of the platform 66 will, for right-hand installations of the hoist, be generally over the rail 18 and, thus, adjacent the wall. This side may thus be called the inboard side of the platform 66 and, in this embodiment, is also the inboard side for left-hand installations.

With the carriage 65 being generally aligned with the inboard side of the platform 66, any weights placed on the step at will be toward the outboard side of the platform and will be an overhung weight. Such weights may be considered as having two force components, one in the plane of the slope of the steps and the other in a plane perpendicular to the slope of the steps. The first-mentioned component will produce a twisting action on the rail B which will be resisted by the rollers 73, 74 and 73, 74 engaging the rail at widely spaced points. This twisting action on the rail B in the plane of the steps is readily resisted by the rail which has a maximum strength against twisting in the plane parallel to the slope of the steps.

The vertical component has a considerable leverage arm and, thus, a very substantial twisting action on the rail B in a plane perpendicular to its length. Heretofore, such twisting action was resisted by providing a stronger and stronger rail member. Means are provided for supporting the outboard side of the platform in the form of a member which progressively engages the uppermost corner of the lip 15 of the stair treads 14 as the platform is advanced up and down the stairways. This engagement of the lips supports this component of the weight and prevents the twisting action on the rail B. While various means can be provided, a preferred embodiment contemplates a skid member in the form of an elongated plate 141 adjustably fastened to the lower edge of the outboard side $6 by means of bolts 13S extending through slots 142 in the plate 141. This plate has an elongated shoe member 144' fastened to its lower edge over which a sheet or sole of antifriction material 145, U shaped in cross section as shown in Figure 4b, is secured. Preferably, the shoe 144' is of resilient construction such as sponge rubber or the like. The sole 145 for the shoe 144' is preferably formed of nylon or Teflon. Further, small pads 146' which will have a low coefiicient of friction when taken in conjunction with the material forming the sole 145 are mounted over the lips of the treads and fastened in place by small brads 147. It is to be noted that in this one instant, the pads 146' are fastened to the stairs by means of nails or the like which will pierce and mar the structure of the stairway. However, such nails or brads are no bigger than would be employed in fastening carpeting to the stairway and, in the event that the hoist had to be removed from the stairway, these pads 146 could be allowed to remain without in any way interfering with the future use of the stairway. it will be noted that the pads 146' prevent wear on the upper corner of the stair lip 15.

The length of the shoe 144' must be at least the distance between two adjacent lips of the stairway and, preferably, each end of the shoe is turned upwardly at an angle which preferably gradually blends into the plane of the sole 145 in a gradual curve as indicated at 149. Thus, any irregularities from tread to tread will not cause any difiiculty. If there is any substantial variation between the over-all slope of the stairway and any one tread, the variation can either be compensated for by cutting away the lip in the event it projects beyond the plane or building up any lip by the use of pads of greater thickness in the event the lip does not extend out to the plane of the overall slope.

Figures 15 and 16 show an alternative embodiment of a skid member useable with the present invention. Here, the plate 151 corresponds to the plate of the preferred embodiment. Mounted at each end of this plate are a pair of roller members 152', 153', and an endless belt 154' is rotatably supported on these rollers. Disposed intermediate the rollers 152' and 153' are a plurality of smaller rollers 156' having lower surfaces all arranged in a plane below the lower edge of the plate 151 and the belt 154 passes over these rollers 156 and any weight or upward forces placed on the belt 154 are trans ferred to the plate 14 through these rollers 156.

These rollers 152', 153' and 156 are all journaled at one end for rotation along the lower edge of the plate 151. These rollers are also journaled for rotation on the other end by a bracket member 158 fastened at its upper end to the plate 151' and extending horizontally over the rollers and thence downwardly over the sides so that the axles of the rollers may extend thereinto. This construction is clearly shown in Figure 16. It will be appreciated that with this embodiment of the invention, the car is advanced up and down the stairway, the belt 154 engages the lips of the stair tread and remains stationary relative thereto while moving relative to the rollers 156'.

It will be appreciated that the pads 146' can be glued to the stair treads if it is desired not to use the brads 147 or, in the alternative, clamps can be employed similar to that used with the brackets 22 for the purpose of fastening the pads 146 to the stair treads.

The principal feature of this construction is that the outboard side of the car be provided with means of a length longer than the distance between two treads which move along with the car to progressively and consecutively contact the various treads for the purpose of supporting the outboard weight placed on the car.

By virtue of this feature, the twisting or torque action on the rail 13 in a plane perpendicular to its length is reduced to practically zero. Thus, the rail may have a much smaller crosssectional area and width than has ever heretofore been possible in what may be called a one-rail stairway hoist.

The power means for driving the car C in either direction along the rail B forms an important part of the present invention. Thus, in the embodiment of the invention shown, the car C is moved in both directions along the rail B by a motor mounted on the interior of the car C and driving through a belt 36 a nut 37 rotatably supported on the car C and engaged with the screw E which extends the full length of the rail B in spaced parallel relationship and thereabove.

The screw E may be mounted relative to the rail in any desired manner but, in the embodiment of the invention shown, a bracket 38 bolted to the rail base 153 by means of a bolt 39 extends upwardly above the upper surface of the rail B. The upper portion of the bracket 38 is welded to the small metallic member 39 having an aperture 40 therein through which the end 41 of the screw E extends. A rubber sleeve 42 surrounding the end 41 is positioned in the aperture 40 and prevents the transmission of vibrations from the screw E to the member 39 and, thus, the rail B. A set screw 43 locks the end of the shaft E in the aperture it). A similar mounting is provided at the opposite end of the rail B.

The nut 37 is supported for rotation in a pair of roller bearings 45 in turn mounted in a cylindrical housing fastened to the left-hand side of the flange 71 by mounting bolts 48. As shown in Figure 5, the right-hand end of the nut 37 extends beyond the bearing 45 and a pulley is mounted on this extension and the belt 36 engages this pulley to rotate the nut 37 relative to the shaft E which, as will be appreciated, is fixed against rotation.

The nut 37 may have a conventional threaded engage ment with the threaded shaft E, but the preferred embodiment of the invention contemplates What is known as a ball-screw connection between the nut 37 and the shaft E. Thus, the shaft E has a continuous helical groove 51 generally semicircular in cross section with an intermediate land 52, the width of which, for reasons which will appear, is at least less than the diameter of the helical groove 51. In fact, the width of the land 52 is preferably less than one-half the width of the groove 51. The nut 37 has an internal diameter greater than the outer diameter of the shaft and has threads of the same pitch which oppose the threads of the shaft E. These opposing threads are filled with a plurality of spherical balls 54, which balls provide the driving connection between the nut 37 and the shaft E. The balls 54 completely fill the grooves of the nut 37 and a tube 55 is provided communicating opposite ends of the nut so that as the nut 37 rotates, the balls may be returned from one end of the nut to the other.

While ball screws per se are not new, it is believed that their application to an elevator stairway is new, particularly when the additional feature is added that the nut is rotatably mounted and the screw is fixedly mounted. By this arrangement, it has been possible to obtain an extremely high mechanical efiiciency driving connection between the car and the fixed portions of the stairway. Also, the nut 37 may be rotated at the same shaft: speed as that of the motor 35 while still obtaining a satisfactory linear velocity of the car C along the rail B. in fact, no other speed-reducing mechanism such gears, gear boxes or the like is required with the preferred embodiment of the invention. Within limits for the same speed motor, the linear speed of the car along the rail B may be varied during the course of manufacture by providing different pitch threads on the shaft E and the nut 37.

Another important feature of the arrangement shown is that if by any chance the nut should lose its balls the lands on the nut being of a lesser width than the helical groove 51 of the shaft E will drop into the grooves 51 and prevent the car from coasting in an unimpeded manner from, say, the top of the stairway to the bottom.

The motor 35 is mounted as is conventional in resilient motor mountings 57, in turn mounted in a bracket 58 supported on the right-hand side of the flange 71 by mounted bolts 59. The mounting of the motor is such that its axis is parallel to the axis of rotation of the nut 37.

The motor 35 drives the belt 36 through a speed responsive clutch indicated generally by the numeral The speed-responsive clutch tif. may be any of the known types of speed-responsive clutches. Er. the pre ferred embodiment of the invention, a mercury-type centrifugal clutch is employed. Thus, the clutch 62 includes an inner driving member 61 keyed to the output shaft of the motor 35 having a flexible tube 63 or" rubber or the like around its outer surface. This tube 63 is hollow and has mercury 64 on the interior thereof The driven member 68 of the clutch 62 surrounds in spaced relationship the flexible tube 63 and is directly connected to a pulley 99 engaged with the belt 36. As the motor 35 drives its output shaft 69* at or approaching its full output speed, the mercury 64 in the tube 63 forces the tube 63 outwardly due to the centrifugal force into frictional driving engagement with the driven member 68. A smooth starting results.

Because of this arrangement, the motor is always at or close to its full operating speed when initially required to deliver power or torque and, ther ore, the motor 35 may be of the type having low start g-torquc characteristics such as split-phase alternating-current motors.

A ring 102, the purpose of which will be described hereinafter, fits over and forms part of the driven member 68 of the clutch 62. The outer surface of this member has a cylindrical surface 163 which forms a brake drum against which braking action is applied to stop the movement of the car in either direction.

Means for braking the car to a stop at either limit of its travel or in the event the operator desires it to stop in the middle of its travel are also provided. in the embodiment of the invention shown, the braking means are mounted on a bracket shown generally at 161 having a base 104 extending parallel to the flange '71 and fastened thereto by means of the bolts 59. The bracket 101 also has a flange 105 extending at right angles to the right of the flange 71 as viewed in Figure 8 and across the lower end of the motor 35, between the motor 35 and the clutch 62.

The brake includes an arcuate length of flexible strip steel 106 having an inwardly facing band of brake material 107 surrounding the outer cylindrical surface 103 of the ring 102. One end of this steel strip 106 is bent back in itself to form an eye 103 which fits over a pin 109 mounted on the bracket flange 105. The other end of the strip 106 has a similar eye 110 through which a pin 111 extends. A pair of helical coil tension springs 112 extend from the pin 111 to the pin 108 and hold the brake band 107 in friction-engaging relationship with the outer surface 103 of the ring 102. The brake is thus normally always engaged.

Means are also provided for releasing the brake when the car is running. In the embodiment of the invention shown, such means include an electrical solenoid 114 having a plunger 115 connected to one end of a lever arm 116 pivotally supported on the bracket flange 105 by means of a pin 117 and connected at its other end to the pin 111. When the plunger 115 is drawn into the solenoid 114 by electrically energizing the solenoid, it will be seen that the lever 116 will act to place the springs 112 under greater tension and relieve the brake pressure on the surface 103.

The brake arrangement shown has what may be termed a differential braking action; that is to say, it provides a greater braking action against one direction of rotation of the surface 103 than it does against the opposite direction of rotation.

The need for such differential braking action becomes apparent when it is realized that the motor rotates at different speeds, depending upon whether the car is being moved upwardly or downwardly. Thus, the synchronous speed of an alternating-current motor is normally 1800 R. P. M. or multiples thereof. When the motor is rotating in a direction to move the car up a stairway and against the force of gravity, substantial amounts of work are required and the operating speed will be somewhat lower than the synchronous speed and approaching 1725 R. P. M. When the motor is rotating to move the car downwardly, in some cases the weight on the car will actually drive the motor and the motor serves as a brake. However, its operating speed will then be somewhat greater than the synchronous speed and might approach 1825 R. P. M.

On the upward movement of the car, de-energizing of t the motor would result in the car stopping as soon as its kinetic energy had been dissipated against the force of gravity. n the downward movement of the car, the force of gravity acts to continue the car in motion. If the same braking effort were used to stop the car from its movement in either direction, difliculty would be experienced in obtaining smooth braking action in both instances. If the brake were properly adjusted for braking the downward movement, then the braking of the upward movement would be sudden and abrupt.

With the brake described and the motor operating in a clockwise direction to move the car down, the brake is what may be termed a self-energizing brake. The braking action is determined to a large degree by the angular wrap of the brake band around the brake drum. On the other hand, when the car is moving up, the braking action required is less. The braking action will be determined to a large degree by the pressure applied by the springs 112. The angle of wrap will have little effect. Thus, in the course of manufacture, the braking effort for the downward movement of the car can be adjusted by using different lengths of brake bands 107 and the upward braking action can be controlled either by adjusting the spring tension of the springs 112 or by substituting different springs.

The brake just described exerts a uniform braking effort in any one direction to bring the car to a stop. With such a uniform braking effort, it is appreciated that for varying loadings on the car, the car will move varying distances after applying the brakes. This becomes apparent when it is realized that the brake must dissipate the kinetic energy of the moving car. This kinetic energy is directly proportional to the product of the weight of the car and the square of the velocity. The velocity remains the same regardless of the loading so that the kinetic energy varies directly as the loading on the car. The invention contemplates, however, so proportioning the kinetic energizes of the car so that the amount of kinetic energy to be braked with the car fully loaded will be substantially equal to that of the kinetic energy to be braked with the car unloaded.

In the embodiment of the invention shown, this is done by so proportioning the mass and dimensions of the ring 102 that its kinetic energy at the speed of rotation of the motor will be at least percent greater than the maximum kinetic energy of the loaded car. In the preferred embodiment of the invention, the dimensions of the ring 102 are so made that its kinetic energy will be at least 1,000 percent greater than the maximum kinetic energy of the moving car. The amount of energy to be dissipated each time the car is stopped is somewhat larger but this is not considered detrimental. The benefits obtained from being able to stop the car at almost the same point after applying the brakes independently of variations of loading on the car are much greater than the slight amount of energy wasted.

It will be noted from Figure 4 that the belt 36 employed is of a kind having teeth 120 on its inner surface which engage with teeth on the faces of the respective pulleys. The belt 36 is held tight by means of an idler wheel 121 pivotally supported on a shaft 122 in turn mounted on a small triangular shaped plate 123 pivoted on the housing 46 by a screw shaft 124. A helical coil tension spring 125 biases the wheel 121 toward the upper surface of the belt 120. A brake shoe 126 is also pivotally upported on the member 123 at a point spaced from the screw 124 and has an arcuate surface 125 adapted to be moved into engagement with a circular surface 128 on the pulley 50. Normally, when the idler wheel 121 is riding on the upper surface of the belt 120, the brake shoe 126 is held in spaced relationship to the surface 128. In the event that the belt 120 should break, the spring 125 biases the member 123 downwardly and pivots the brake shoe 126 into engagement with the surface 128. A braking action results which will prevent the car from falling freely down the rail Means are provided between the car and the rail for coacting to de-energize the motor 35 and the solenoid 114 to apply the brakes and bring the car to a stop at either limits of its travel. In the embodiment of the invention shown, a cam plate 130 is fastened to the inner wall 20 of the rail B at either end thereof. Screws 131 are used to mount the cam plate 130 in position. This cam plate is relatively elongated and has a beveled corner 132 facing away from the ends of the rail B. A cam follower in the form of a shaft 134 extends through an opening 135 in the carriage base 70 to a position where it will be engaged by the cam surface 132. The follower 134 is mounted on the end of member 136 slidably supported in a vertical direction on the flange 71. The upper end of the member 136 is bent outwardly from the flange 71 as at 138 and a microswitch 139 having an actuating arm 137 is mounted above the portion 138 so that the arm 137 will be engaged and, thus, the switch 139 actuated whenever the cam follower strikes the cam plate 130. The cam plate 130 is shown as being relatively elongated and preferably has a length at least greater than the maximum tolerances on the stopping distances of the car so that when the car is brought to a stop at either limit of its travel, the follower 134 will be riding on the upper fiat surface of the cam 130 substantially as is shown by the dotted lines in Figure 6. Actuation of the switch 139 acts in a manner to be described to bring the car to a halt.

As will appear, the control circuit requires that the switch 139 in the embodiment of the invention described has both a single-pole, double-throw switch and a singlepole, single-throw switch, as it was found cheaper to purchase two switches having the desired and required contacts rather than a single switch having all the contacts combined. The latter referred to switch is indicated by the reference character 139'.

The embodiment of the invention shown also contemplates means for setting up a set of conditions whereby once the car is started and stopped, it will then restart in the opposite direction. While this can be accomplished by means of gear-shifting arrangements each time the car is started in one direction, the preferred embodiment of the invention provides for reversing the starting connections of the motor 35 once the car has commenced to move in one direction along the rail B. In the embodiment of the invention shown, such means contemplates a switch of the double-pole, double throw variety which is actuated as soon as the car commences to move in either direction. Thus, a shoe 142 slidably engages the upper surface of the rail B and is articulately supported on the lower end of a lever arm 143 in turn pivotally supported on the flange 71 by means of a screw 144 extending through a longitudinal slot 145 in the arm 143. A helical coil tension spring 146 extends from a pin 147 on the upper end of the arm 143 to the screw 144 and acts to pull the arm 143 on either side of a deadcenter line 148 shown generally in Figure 12. A slide 150 is slidably supported on the flange 71 adjacent the upper end of the member 143 and has a pair of stop pins 151, 152 extending outwardly in spaced relationship on each side of the upper end of the arm 143.

In Figure 12, the arm 143 is shown in a position either with the car moving to the right or stopped after having been moved to the right. When the car is moved to the left, the brake shoe 142 bearing on the upper surface of the rail B is frictionally prevented from moving and shifts the arm 143 through the dead-center axis 148 to the position shown in dotted lines in Figure 12. With the arm 143 in this position, the slide 150 is moved to the left to engage the operating pin 154 on the switch 140. The arm 143 will remain in the position shown in dotted lines in Figure 12 during the entire movement of the car to the left and until the car is again moved toward the right.

Electric power for the motor 35 and the solenoid 114 and the control signal for starting and stopping the car from either end of the rail B is conducted to the car by means of brushes contacting electrically energized rails on the interior of the rail B. As will appear, only three conductors and three brushes are needed. Thus, in the embodiment of the invention shown, three conductors 155, 156 and 157, each formed of a flat strip of copper, are imbedded in electrically insulating material 158 with flat surfaces exposed to the interior of the rail B are provided. The plane of the strips 155 and 157 is generally horizontal and the bare surfaces face downwardly and upwardly respectively. The strip 156 extends generally vertically and its bare surface extends to the left as viewed in Figure 10. The insulating material 158 is in turn supported in a metallic U-shaped frame 159 of a dimension to fit snugly on the inside of the rail B and against the inner surface of the wall 20. The ends of the leg of the U frame 159 are reversely bent upon themselves and around the insulation 158 to assist in retaining the strips 155 and 157 in permanently assembled relationship.

In Figure .10, the brush for engaging the conductor rail 156 is shown. This brush consists of a contact member 161 slidably supported between the sides of a U- shaped clip 162 mounted on a block of electrically insulating material 163 in turn mounted on a downwardly turned flange 164 of the carriage base 70. A helical coil compression spring 165 biases the contact 161 toward the member 156.

Figure 9 shows the brush employed for engaging the upper contact rail 155. This brush is comprised of a contact member 166 extending upwardly from a horizontal- 1y extending flat spring 167 mounted at its left-hand end by means of a screw 168 on the insulating material 163. A spring 169 also mounted on the material 163 and extending to the right biases the contact 166 upwardly into sliding engagement with the rail 155. A similar contact 166' is employed for contacting the bottom rail 157.

The invention also contemplates means on the leading edges of the platform 65 for bringing the car to a stop in the event something should become lodged between the moving car and the steps which is simple in construction and easily manufactured. Referring now to Figure 2, the leading edge of the step has a semielliptical piece of rubber tube extending across its entire width. The edges of the tube 175 are bent back upon themselves as at 176 and are gripped between reversely bent portions 177 of a metal strip 178 in turn mounted on the flange 82. A similar bumper 175' is mounted on the lower edge of the riser 81.

The member 175 in effect serves as a flexible bumper for the car C. Operating in conjunction with this bumper, however, is means for de-energizing the motor 35 and applying the brakes to bring the car to a stop.

A control bar 180 in the form of a metallic rod is biased against the inner surface of the rubber bumper 175 by means of a push rod 181 articulately connected to the rod 180 at its center and slidably supported in a direction parallel to the surface of the step by a bracket 182 in an opening 183 in the flange 82. A helical coil spring 185 bearing against the bracket 182 and a washer 186 on the push rod 181 biases the rod 181 to the right as viewed in Figure 3 and thus presses the control bar 180 against the inner surface of the bumper 175. A limit switch 188 is mounted on the under surface of the step and has a control arm 187 engaged by a nut 190 threaded on the left-hand end of the shaft 181, when the shaft 181 is in its right-hand position. Whenever the push rod 181 is biased or moved to the left, however, the arm 187 of the switch 188 moves to operate the contacts of the switch 188. These contacts, as will appear, do-energize the motor 35 and the solenoid 114.

The push rod 181 is moved to the left by pressure on the outer surface of the rubber bumper 175. This is shown generally by the arrow 192 of Figure 3 which compresses the rubber bumper 175 substantially as shown at 193 and pushes the upper end of the rod 130 to the left. It will be noted that the opposite or lower end of the rod 180 continues to bear against the inner surface of the rubber bumper 75 and acts as a pivot point. Movement of the upper end of the rod 180, however, causes the push rod 181 to move a suflicient distance to actuate the switch 188. The construction shown is extremely simple in operation and economical to manufacture. A similar arrangement is shown on the lower edge of the riser 81 and includes a switch 189 shown in Figure 14.

In the embodiment of the invention shown in Figure l, the car C also includes a handle shown generally at 195 including a pair of parallel extending legs 196 interconnected at the top by a horizontal member 197. The lower ends of the legs 196 are bolted to the flange 85 in a manner not shown. The legs 196 are hollow and a pair of electrical control Wires extend through one of the legs to a switch mounted on the inside of the horizontal portion 197 and actuated by a push button 198 extending through the lower side of the portion 197. The switch is not shown in Figure l but is indicated generally at 199 in Figure 14 as having normally open contacts.

The preferred embodiment of the invention also contemplates a switch (not shown) to be placed at each end 'brush 161.

of the rail B with normally open contacts. The upper switch is indicated by the numeral 200 in Figure 14 and the lower switch is indicated by the numeral 201. As will appear, closing of the contacts of either one of these switches will start the car in operation and cause it to move in the direction as determined by the position of the arm 143.

Figure 14 shows a schematic wiring diagram of the control circuit embodying the present invention. In this diagram, like numbers have been used to designate like parts in the other figures. Thus, the numerals 155, 156 and 157 indicate the rails or busses extending lengthwise on the interior of the rail with the brushes 166, 161 and 1715 respectively in sliding electrical contact therewith. The wires 155 and 157 are connected to a source of electrical power indicated by L and L The wire 156 is a control wire and is energized whenever the contacts of the switches 200 and 201 are closed. These switches, as previously indicated, are positioned at either end of the rail B.

The motor 35 includes a main or running winding 210, a starting winding 211, a centrifugal switch 212 which opens as the motor approaches running speed and a thermo overload switch 213. One terminal of the centrifugal switch is connected to the starting winding 211 through Wire 214. In a like manner, one terminal of the overload switch 213 is connected to one terminal of the starting winding 210 by wire 215.

The control circuit also includes a relay 220 having normally open contacts 221 and a time-delay switch 222 including a motor 223 which drives a pair of timing cams 224 and 225 which, in turn, actuate respectively a single-pole, single-throw switch 226 and a single-pole, double-throw switch 227.

The circuit also includes the emergency stop switch 188 having normally closed contacts and a similar emergency stop switch 189 which is mounted on the back of the riser panel 81.

Switches 140 and 140 of the single-pole, double-throw type are also included, the function of which, when shifted from one pole to the other, is to reverse the direction of current to the starting winding 211 and, thus, cause the motor to start in opposite directions.

The circuit also includes a starting switch 199 which is located on the interior of the horizontal portion 197 of the handle 195.

The circuit further includes switches 139 and 139' which are of the single-pole, double-throw and singlepole, single-throw type respectively. These switches act, when operated, to stop the motor 35 and de-energize the solenoid 114 to apply the brakes.

To describe the operation of the circuit diagram of Figure 14, it will be assumed that the car has been moving to the right and has been stopped somewhere midway in the length of its travel. In this position, the wire 215 is continuously energized through the normally closed contacts of the overload switch 213, the wire 240 and the slide 170 to the bus 157. In this respect, the wire 215 may be considered a common bus and it is shown in slightly heavier lines for the purposes of clarity. The other switches are all in the position shown with the solenoid coil 114 de-energized and, thus, with the brake applied.

The car may be started from either end of the rail B by depressing either the switch 201) or the switch 201, thus energizing the control bus 156 and wire 231 through The car may also be started by closing the normally open contacts of switch 199 which energizes the wire 231 through the brush 166 and wire 230.

In either event, a circuit is completed to energize the relay 220, the circuit being traceable from wire 231 through the closed contacts of switch 188, wire 232, the closed contacts of switch 189 to wire 233, the closed contacts of the switch 139', the wire 243 and the energization coil of the relay 220 to the wire 215.

Energization of the relay 220 closes its normally open contacts 221 which completes a circuit to energize the solenoid 114 and the running and starting windings 210 and 211 respectively. The circuit is traceable from the wire 233, the now closed contacts 221 and the wire 245, through the solenoid 114 to wire 215, or from wire 245 through starting winding 210 to the wire 215, or from wire 245 through the right-hand contacts of switch 141), wire 247, the starting winding 211, wire 214, the closed contacts of the centrifugal starting switch 212, wire 24%, the right-hand contacts of the switch to the wire 215.

The brake is thus released and the motor is energized in a direction to move the car to the left. As the motor comes up to full speed, the speed-operated clutch is engaged to so move the car and, at the same time, the centrifugal switch 212 is opened to de-energize the starting winding 211.

As soon as the car initially starts to move to the left, the arm 143 is shifted to the right-hand position, thus moving the arms of the switches 140 and 140' to the lefthand position. In this position, the starting winding 211 will be energized to drive the car toward the right except for the fact that the switch 212 is now open and remains so as long as the motor runs.

The car will continue to run in the direction indicated so long as either the switch 200, 201 or 199 remains closed. Either of these switches may be opened instantaneously and reclosed without effect, the car continuing to move in the same direction. If any of the switches, however, are allowed to remain open until the centrifugal switch 212 closes and then is again closed, the motor will be plugged to a stop and will immediately start to rotate in the opposite direction and drive the car in the opposite direction.

If it be assumed that the car continues to move to the left until the cam follower 134 rides up on the cam 130, then the switches 139 and 139' are moved to a position opposite from that shown in Figure 14. Opening of the contacts of the switch 139' immediately deenergizes the relay 220, and, thus. the running winding 210 and the solenoid 114. When the solenoid 114 is de-energized, the brakes are applied as previously described.

Shifting of the arm of the switch 139 to the upper position energizes the timing motor of the time-delay relay 222, the circuit being traceable from the wire 233, the energization of which was previously described, the coil 223, the left-hand contacts of the switch 227, wire 250, the now closed upper contacts of the switch 139 to the wire 215. Energization of the motor of the timedelay relay 222 starts the cams 224 and 225 moving, it being assumed that one of the switches 199, 200 or 201 remains closed. After a predetermined time interval, the cam 224 moves the arm of switch 226 to the right, thus closing its right-hand contacts. Closing of these contacts completes a circuit from the wire 233 to the wire 243 and, thus, re-energizes the coil 220. The motor 35 is thus energized to rotate in a direction to move the car to the right in a manner as previously described. The time-delay relay continues to operate, however, until the cam 225 moves the arm 227 to the right and de-energizes the coil 223.

When the car has moved to the right a sufficient distance, the cam follower 134 drops off of the cam 130, thus reclosing the lower contacts of the switches 139 and 139'. Closing of the lower contacts of the switch 139 again re-energizes the timer motor 223 which continues to operate until the arm of the switch 227 is moved to the left, at which time the motor 223 is again deenergized. During this latter operation of the timer, the switch 226 is also opened, but without effect because the contacts of the switch 139' which are in parallel therewith are again closed as above pointed out.

The principal function of the timer 222 is to insure that when the car has reached either limits of its travel and is automatically stopped by means of the cams 130 and the cam follower 134, the rotor of the motor will have had a sufiicient time to have slowed to a speed at which the centrifugal switch 212 is again closed. It will be appreciated that when the brake 114 is applied and the motor rotor slows down, the speed-responsive clutch will disengage and the rotor of the motor is then rotating freely without any braking action. In the absence of the time delay, it would be possible for an operator to close one of the switches 19d, 2&0 or 261 and re-energize the motor 35 while it is still coasting when the centrifugal switch 212 is not closed. If this should happen, the car would be driven in the same direction over the end of the limit cams and serious damage would result.

On the other hand, if a sufficient time delay is allowed to make sure that the centrifugal switch 212 is closed before the motor can be re-energized, it will be appreciated that the motor will be dynamically braked to a stop and driven in the opposite direction to move the car in the proper direction.

The elevator shown is extremely simple to install and operate. The brackets 22 are fastened to the lips of the stair treads. The rail B with the threaded shaft E and the carriage 65 in place are then fastened to the brackets. The car 66 is then fastened to the flange 71 of the carriage and the angle of its step adjusted so as to be horizontal. Electric power is connected to either end of the rail by plugging into a conventional light socket. The wear and friction pads for the lips of the treads are then placed in position. The car is then ready to operate.

Using the construction shown, it has been found possible to use a A horsepower, split-phase, alternatingcurrent motor. The speed-operated clutch permits the use of this low starting torque motor because the motor is operating at substantially full speed when it is ongaged to drive the car in either direction. The braking action of the brake is inherently greater on the downward movement of the car than on the upward movement of the car, resulting in an extremely efiicient braking action. The kinetic energy storing arrangement enables the car to be braked to a complete stop in substantially the same distance along the rail regardless of variations in the load on the car. The use of a rotating nut on the car engaging a stationary fixed shaft has enabled the elimination of the usual speed-reducing arrangement and the use of the ball type nut and screw gives such high mechanical efficiency that a lower horsepower motor than ever heretofore thought possible can be employed.

In the event the belt 120 should break, a safety brake is applied to prevent the car from falling freely down the stairway. in the event the balls should come free, the lands on the nut will fall into the threads on the screw and prevent the car from falling freely away.

The control circuit enables the use of only three electrical connections between the rail and the car where, heretofore, four and oftentimes five sliding electrical connections were required.

The invention has been described in detail in connection with a preferred embodiment. It will be appreciated that modifications and alterations will occur to others upon a reading and understanding of this specification and it is our intention to incnide all such modifications and alterations, event though differing radically in appearance, insofar as they come within the scope of the appended claims.

Having thus described our invention, we claim:

1. In an electrically-powered stairway elevator including a reversing motor operable to move a load-carrying ing platform between defined terminal positions: control means for delaying energization of said motor when said platform is at said terminal positions, said control means comprising first switch means responsive to one direction of movement of said platform for establishing a rotationdirecting starting circuit for said motor, second switch means responsive to the opposite direction of movement of said platform for establishing an opposite rotationdirecting starting circuit for said motor, speed-responsive switch means for opening said starting circuits in response to a predetermined operating speed of said motor, normally-closed third switch means for establishing a running circuit for said motor, means responsive to arrival of said platform at said terminal positions for opening said third switch means, normally-open fourth switch means for re-establishing said running circuit, and timer means actuated in response to opening of said third switch for effecting predetermined delayed closing of said fourth switch, said predetermined delay being of sufiicient duration to permit closing of said speed-responsive switch prior to said closing of said fourth switch.

2. A combination as defined in claim 1, including a speed-responsive clutch operatively connecting said motor to the load at a predetermined operating speed of said motor, and brake means actuated in response to opening of said running circuit for engaging the driven portion of said clutch, whereby said motor is disconnected from the load when said running circuit is opened.

3. In a power-driven stairway elevator having a platform adapted to carry loads between an upper terminal and a lower terminal which may vary from a minimum to a maximum on different trips, said elevator having rotary drive means for driving said platform at a predetermined velocity, said drive means including in combination an electric motor, a rotary speed-responsive clutch, opera tively associated with said motor for disconnecting said motor from said drive means when said motor is deenergized and its speed drops below a predetermined speed below its full load operating speed, brake means engageable with the driven member of said clutch in response to de-energization of said motor for braking said platform to a stop and a flywheel associated with the driven member of said clutch having a kinetic energy at the operating speed of said motor at least 1,000% greater than the kinetic energy of the maximum load to be carried by the platform at the predetermined velocity of movement of the platform whereby said brake will bring said platform to a stop in substantially the same distance irrespective of the load on said platform.

4. In a power driven stairway elevator having a platform adapted to carry a load which may vary from a minimum to a predetermined maximum between an upper and lower terminal on said stairway, said elevator having rotary drive means including an electric motor for driving said platform at a predetermined velocity, a. rotary speed-responsive clutch associated with said drive means, and operable to disconnect said motor from said drive means when said motor is de-energized and its speed is reduced a predetermined amount below its full load speed; brake means engageable with the driven end of said clutch when said motor is de-energized whereby to bring said platform to a stop; a flywheel associated with said driven end of said clutch having a kinetic energy at the speed of operation at least 1,000% greater than the kinetic energy of the maximum load at said predetermined velocity whereby the total kinetic energy reacting on said brake means is substantially uniform irrespective of the load on said platform and said platform will thus be brought to a stop at generally the same point along the stairway notwithstanding variations in the load of the platform, said brake means including a band frictionally engaged with said drive means and being of the self-energizing type when said drive means is rotating in a direction to move the platform toward the lower terminal and of the pressure type when said drive means is rotating in a direction to drive said platform towards said upper terminal whereby a greater braking effort will be exerted in a downward direction than in an upward direction and 17 the platform may be brought to a smooth stop regardless 2,212,388 of the direction in which it is moving. 2,227,111 2,270,735 References Cited in the file of this patent 2,328,817 UNITED STATES PATENTS 2 122 323 446,621 Eaton Feb. 17, 1891 2j466j989 1,161,255 Schnitzer Nov. 23, 1915 2 527 97 1,511,055 Entwistle Oct. 7, 1924 2 10 2 3 1,618,644 Dickson Feb. 22, 1927 10 2 9 9 2,042,937 Henricksen June 2, 1936 2,114,242 White Apr. 12, 1938 2,207,544 Knudsen July 9, 1940 1,094

18 Cheney Aug. 20, 1940 Sturn Dec. 31, 1940 Knudsen Jan. 20, 1942 Le Tourneau Sept. 7, 1943 Zimmerman May 21, 1946 Rowe Aug. 17, 1948 Hertrick Apr. 12, 1949 Todd Oct. 31, 1950 Hamilton Sept. 9, 1952 Scott Nov. 25, 1952 FOREIGN PATENTS Great Britain Jan. 15, 1907 

